The invention relates to the field of electronic components and is intended for application in the field of gas-filled discharge gaps having at least two electrodes, in which a vitreous electrode activation compound consisting of several components is applied on at least one of the electrodes in order to guarantee the starting characteristics.
In discharge gaps such as overvoltage arresters or switching spark gaps, in order to guarantee the desired operating behavior for instance starting voltage (particularly d.c. sparkover voltage), time to sparkover, static sparkover voltage, dynamic sparkover voltage, holdover voltage, and glow voltage various measures must be tuned to one another, such as the constructional design of the electrodes, the type and pressure of the gas filling, and the selection of the activation compound that is disposed on the active surfaces of the electrodes. To set the d.c. sparkover voltage V.sub.s, it is common to use a vitreous electrode activation compound containing sodium silicate (Na.sub.2 SiO.sub.3), cesium silicate (CS.sub.2 SiO.sub.3), and metallic titanium (Ti) as base components and smaller fractions of sodium tetraborate (Na.sub.2 B.sub.4 O.sub.7) and magnesium oxide (MgO) as additives. In those prior art activation compounds, the base component sodium silicate is provided in an amount approximately four to six times greater than the other base components, cesium silicate and titanium. An activation compound of such composition has proven to be out of correspondence with the elevated demands placed on the constancy of the d.c. sparkover voltage under surge current load and alternating current load.